Question 5 of the 2005 Football Rules quiz states:

Fourth and 10 with the nose of the ball touching team B's 20 yardline. A1's pass is incomplete. The officials should:

a) Move the ball, not the chains, so that the nose of the ball is on team B's 20 yardline
b) Move the chains, not the ball, so that the tail of the ball is touching team B's 20 yardline

What would be the NFHS mechanic?

b. move the chains, not the ball.

4th down is no different than any other down- on an incomplete pass bring the ball back to where it was.

Your boxman has to then move a ball length.

yup, this is something that is missed by a large number of wing men. I know I missed it for a few seasons until someone point out that the chains move, not the football.

Agreed! You also will be questioned by an unexperience chain crew when you tell them they have to move the length of the football. They may, or may not eventually figure it out.

Thanks guys! And now that I've thought about it, it makes perfect sense...especially if the ball were on the one inch line at a change of possession.

Canadian Ruling
 

In Canada, we do A. The tip of the ball is the line of scrimmage so that at a change of possession the new LOS remains the same. So we would move the ball (and the chains because they would going the other way).

The LOS is never inside the one yard line so we do not have to worry about moving the ball such that part of it would be inside the EZ.